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Thu, 28 Aug 2025 08:53:02 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id dKHvBu4YsGjeMwAAD6G6ig (envelope-from ); Thu, 28 Aug 2025 08:53:02 +0000 Message-ID: <2182c715-aaf1-46d1-809e-e4142bc083af@suse.cz> Date: Thu, 28 Aug 2025 10:53:01 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/2] mm/show_mem: Add trylock while printing alloc info Content-Language: en-US To: Yueyang Pan Cc: Andrew Morton , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Usama Arif , linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org References: <7e2bc96faab1a338829e549246189ad96e6c866b.1756318426.git.pyyjason@gmail.com> <20250827150619.4e468e68988f224f9f9bea6f@linux-foundation.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Stat-Signature: o3md4y75ch4jsigxce8onp7tpdkbnd8s X-Rspam-User: X-Rspamd-Queue-Id: B58C3140004 X-Rspamd-Server: rspam05 X-HE-Tag: 1756371183-103154 X-HE-Meta: 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 I3f8gNNN +lKUjR9A/7pV41poEEFijKg+QK+AxNu7QTPbP54+vayWSg47xlot7GBfqf3qpSx7D00d5xbe3wvvuWClic344zox63gAoTUl8buZd8J69x1cHxPB2CshT4e3hwexJ7YxLdLSo2HWzZo6QFiujlJncsF9y7nIQdxe1lAAqJeLPdm+7C+s6NrqOz1fiM7xScn1WmruBc3Ojq8Ma3Np2hE5IxTjfMXgYSgty2MIJALoe6DwOnggPKqmANKrcxwVftDfCZ66Q6mUQYDC0skJSyRkGPzrQIEgSs2X5f516JZffxius74fnVqT7Rn1xlTODfYj3NgpC6l3vfS8tERGmdQiVpU+3W8CsQH4DARRg X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/28/25 10:47, Yueyang Pan wrote: > On Thu, Aug 28, 2025 at 10:41:23AM +0200, Vlastimil Babka wrote: >> On 8/28/25 10:34, Yueyang Pan wrote: >> > On Wed, Aug 27, 2025 at 03:06:19PM -0700, Andrew Morton wrote: >> >> On Wed, 27 Aug 2025 11:34:23 -0700 Yueyang Pan wrote: >> >> >> >> > In production, show_mem() can be called concurrently from two >> >> > different entities, for example one from oom_kill_process() >> >> > another from __alloc_pages_slowpath from another kthread. This >> >> > patch adds a mutex and invokes trylock before printing out the >> >> > kernel alloc info in show_mem(). This way two alloc info won't >> >> > interleave with each other, which then makes parsing easier. >> >> What about the rest of the information printed by show_mem() being interleaved? > > Thanks for your feedback, Vlastimil. We cannot use trylock for the rest > part as node filter can be different. Right. > Do you think we need a lock to prevent the whole show_mem() from being > interleaved and to acquire it at the very beginning? Will it be too > heavy? It might be risky so perhaps let's not. Guess we can disentangle by dmesg showing the thread id prefix.